CN109417215B - Self-adjusting electromagnetic coupler with automatic frequency detection - Google Patents

Abstract

Electromagnetic coupler systems including built-in frequency detection, and modules and devices including such systems. One example of an electromagnetic coupler system includes an electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port, the electromagnetic coupler including a main line extending between the input port and the output port and a coupled line extending between the coupled port and the isolated port, the electromagnetic coupler configured to generate a coupled signal at the coupled port in response to receiving an input signal at the input port. The adjustable termination impedance is connected to the isolated port. A frequency detector is connected to the adjustable termination impedance and the coupling port and is configured to detect a frequency of the coupling signal and provide an impedance control signal to tune the adjustable termination impedance based on the frequency of the coupling signal.

Description

Self-adjusting electromagnetic coupler with automatic frequency detection

Cross Reference to Related Applications

The present application claims the benefit of co-pending U.S. provisional applications nos. 62/333,368 and 62/454,971 under 35u.s.c. § 119(e) and PCT No. 8, filed 2016, 9, 2017, 2, 6, respectively, each of which is incorporated herein by reference in its entirety for all purposes.

Background

Directional couplers are widely used in Front End Module (FEM) products such as radio transceivers, wireless handheld devices, and the like. For example, a directional coupler may be used to detect and monitor Radio Frequency (RF) output power. When an RF signal generated by an RF source is provided to a load, such as an antenna, a portion of the RF signal may be reflected from the load back to the RF source. An RF coupler may be included in a signal path between an RF source and a load to provide an indication of forward RF power of an RF signal propagating from the RF source to the load and/or an indication of reverse RF power reflected from the load. RF couplers include, for example, directional couplers, bidirectional couplers, multiband couplers (e.g., dual-band couplers), and the like.

Referring to fig. 1, RF coupler 100 generally has a power input port 102, a power output port 104, a coupled port 106, and an isolated port 108. Electromagnetic coupling mechanisms, which may include inductive or capacitive coupling, are typically provided by two parallel or overlapping transmission lines, such as microstrips, striplines, coplanar lines, and the like. The transmission line 110 extending between the power input port 102 and the power output port 104 is referred to as a main line, and can provide most of the signal from the power input port 102 to the power output port 104. The transmission line 112 extending between the coupled port 106 and the isolated port 108 is referred to as a coupled line and may be used to extract a portion of the power propagating between the power input port 102 and the power output port 104 for measurement. When the termination impedance 114 is presented to the isolated port 108 (as shown in fig. 1), an indication of the forward RF power propagating from the power input port 102 to the power output port 104 is provided at the coupled port 106. Similarly, when the termination impedance is presented to the coupled port 106, an indication of reverse RF power transmitted from the power output port 104 to the power input port 102 is provided at the isolated port 108. In various conventional RF couplers, the termination impedance 114 is typically implemented by a 50 ohm shunt resistor.

Disclosure of Invention

Aspects and embodiments are directed to an electromagnetic coupler having built-in frequency detection and the ability to automatically tune the termination impedance based on the detected frequency, thereby improving coupler operation.

According to one embodiment, an electromagnetic coupler system includes an electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port, the electromagnetic coupler including a main transmission line extending between the input port and the output port, and a coupled transmission line extending between the coupled port and the isolated port, the electromagnetic coupler configured to generate a coupled signal at the coupled port in response to receiving an input signal at the input port. The electromagnetic coupler system also includes an adjustable termination impedance connected to the isolation port, and a frequency detector connected to the adjustable termination impedance and the coupled port, the frequency detector configured to detect a frequency of the coupled signal and provide an impedance control signal to tune the adjustable termination impedance based on the frequency of the coupled signal. The electromagnetic coupler system may further include a controller coupled to the frequency detector, the controller configured to receive the impedance control signal from the frequency detector and tune the adjustable termination impedance in response to the impedance control signal.

According to another embodiment, a self-adjusting electromagnetic coupler assembly includes an electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port, the electromagnetic coupler including a main line extending between the input port and the output port, and a coupled line extending between the coupled port and the isolated port, the electromagnetic coupler configured to generate a coupled signal at the coupled port in response to receiving an input signal at the input port. The self-adjusting electromagnetic coupler assembly also includes an adjustable termination impedance connected to the isolation port, and a frequency detector connected to the coupling port, the frequency detector configured to detect a frequency of the coupling signal and provide an impedance control signal to tune the adjustable termination impedance based on the frequency of the coupling signal. In some examples, the self-adjusting electromagnetic coupler assembly may further include a controller coupled to the frequency detector, the controller configured to receive the impedance control signal from the frequency detector and tune the adjustable termination impedance in response to the impedance control signal.

According to another embodiment, a self-adjusting electromagnetic coupler system includes an electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port, the electromagnetic coupler including a main line extending between the input port and the output port, and a coupled line extending between the coupled port and the isolated port, the electromagnetic coupler configured to generate a coupled signal at the coupled port in response to receiving an input signal at the input port. The self-adjusting electromagnetic coupler system also includes an adjustable termination impedance connected to the isolation port, and a frequency detector connected to the adjustable termination impedance and the coupled port, the frequency detector configured to detect a frequency of the coupled signal and tune the adjustable termination impedance based on the frequency of the coupled signal.

In one example, the adjustable termination impedance includes a tunable resistor-capacitor-inductor circuit. In another example, the adjustable termination impedance comprises a network of switchable impedance elements. For example, the network of switchable impedance elements may comprise at least one resistive element, at least one capacitive element and at least one inductive element.

In one example, the frequency detector comprises a plurality of frequency selective components, a respective plurality of envelope detectors coupled to the plurality of frequency selective components, and at least one voltage comparator connected to the plurality of envelope detectors, wherein the voltage comparator is configured to compare outputs of the plurality of envelope detectors and to generate an output signal in response to the comparison. The frequency detector may be configured to provide the impedance control signal based on an output signal from the at least one voltage comparator. In another example, the plurality of frequency selective components includes a plurality of band pass filters, each band pass filter having a unique frequency pass band. In another example, the plurality of frequency selective components includes a plurality of narrow band amplifiers. In one example, the plurality of envelope detectors comprises a plurality of diode-based detectors. The frequency detector may further comprise an analog-to-digital converter connected to the at least one voltage comparator, configured to convert the output signal from the at least one voltage comparator into a digital signal. In one example, the frequency detector further comprises a digital decoder connected to the analog-to-digital converter, which is configured to provide the impedance control signal/information based on a digital signal received from the analog-to-digital converter. The frequency detector may further comprise a digital inverter connected to the output of the at least one voltage comparator.

According to another embodiment, an electromagnetic coupler system includes an electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port, the electromagnetic coupler including a main transmission line extending between the input port and the output port, and a coupled transmission line extending between the coupled port and the isolated port, the electromagnetic coupler configured to generate a coupled signal at the coupled port in response to receiving an input signal at the input port. The electromagnetic coupler system also includes an adjustable termination impedance connected to the isolation port, a frequency detector connected to the coupling port and configured to determine a frequency of the coupling signal and provide an indication of the frequency of the coupling signal, and a controller connected to the frequency detector and the adjustable termination impedance, the controller configured to receive the indication of the frequency of the coupling signal from the frequency detector and apply a control signal to the adjustable termination impedance to tune the adjustable termination impedance based on the frequency of the coupling signal.

In one example, the adjustable termination impedance includes a tunable resistor-capacitor-inductor circuit. In another example, the adjustable termination impedance comprises a network of switchable impedance elements. The network of switchable impedance elements may comprise at least two resistive elements. The network of switchable impedance elements may further comprise at least one capacitive element or at least one inductive element.

In one example, the frequency detector comprises a plurality of frequency selective components, a respective plurality of envelope detectors coupled to the plurality of frequency selective components, and at least one voltage comparator connected to the plurality of envelope detectors, the voltage comparator being configured to compare outputs of the plurality of envelope detectors and to generate an indication of the frequency of the coupled signal based on the comparison. In one example, the plurality of frequency selective components includes a plurality of band pass filters, each having a unique frequency pass band. In another example, the plurality of frequency selective components includes a plurality of narrow band amplifiers. In one example, the plurality of envelope detectors comprises a plurality of diode-based detectors.

Another embodiment is directed to a coupler module comprising an example of any of the electromagnetic coupler systems described above. The coupler module may also include a package substrate, an electromagnetic coupler system formed on the package substrate, and a plurality of connection pads for connecting the electromagnetic coupler system to an external electronic device.

Another embodiment is directed to a wireless device that includes an example of any of the electromagnetic coupler systems described above, an antenna coupled to an output port of the electromagnetic coupler, and a transceiver coupled to an input port of the electromagnetic coupler and configured to generate an input signal. The wireless device may also include a power amplifier connected between the transceiver and the electromagnetic coupler input port, the power amplifier configured to amplify an input signal. In one example, the wireless device further includes a sensor connected to the electromagnetic coupler coupling port, the sensor configured to receive the coupled signal. In another example, the wireless device further includes an antenna switch module coupled between the electromagnetic coupler output port and the antenna and between the antenna and the transceiver. The wireless device may also include a baseband subsystem coupled to the transceiver. In one example, the wireless device further includes at least one of a power management subsystem, a battery, at least one memory, and a user interface.

According to another embodiment, an electromagnetic coupler system includes a bidirectional electromagnetic coupler having a first power signal port, a second power signal port, a third port, and a fourth port, the electromagnetic coupler including a main transmission line extending between the first and second power signal ports, and a coupled transmission line extending between the third and fourth ports. The electromagnetic coupler may be configured to generate a forward coupled signal at the third port in response to receiving an input signal at the first power signal port in a forward mode of operation and to generate a reverse coupled signal at the fourth port in response to receiving an input signal at the second power signal port in a reverse mode of operation. The electromagnetic coupler system also includes a first adjustable termination impedance, a second adjustable termination impedance, and a switching network operable to selectively configure the bidirectional electromagnetic coupler between a forward mode of operation and a reverse mode of operation, selectively connect the first adjustable termination impedance to the fourth port when the bidirectional electromagnetic coupler is in the forward mode of operation, and selectively connect the second adjustable termination impedance to the third port when the bidirectional electromagnetic coupler is in the reverse mode of operation. The electromagnetic coupler system also includes a controller configured to control the switch network, and a frequency detector coupled to the third and fourth ports, the frequency detector configured to determine a frequency of the forward coupling signal and the reverse coupling signal and provide an impedance control signal to tune the first and second adjustable termination impedances based on the frequency of the forward and reverse coupling signals, respectively.

In one example, the frequency detector is configured to provide an impedance control signal to the controller, the controller further configured to tune the first and second adjustable termination impedances in response to the impedance control signal.

In one example, the controller is configured to receive an input control signal specifying a desired mode of operation of the bi-directional electromagnetic coupler and to actuate the switch network in response to the input control signal.

In one example, each of the first and second adjustable termination impedances includes a tunable resistor-capacitor-inductor circuit. In another example, each of the first and second adjustable termination impedances comprises a network of switchable impedance elements. In one example, the network of switchable impedance elements comprises at least one resistive element, at least one capacitive element and at least one inductive element.

The frequency detector may include a plurality of frequency selective components, a respective plurality of envelope detectors coupled to the plurality of frequency selective components, and at least one voltage comparator connected to the plurality of envelope detectors, the voltage comparator configured to compare outputs of the plurality of envelope detectors and generate an output signal in response to the comparison, the frequency detector further configured to provide an impedance control signal based on the output signal from the at least one voltage comparator. In one example, the plurality of frequency selective components includes a plurality of band pass filters, each having a unique frequency pass band. In another example, the plurality of frequency selective components includes a plurality of narrow band amplifiers. In one example, the plurality of envelope detectors comprises a plurality of diode-based detectors. The frequency detector may further comprise an analog-to-digital converter connected to the at least one voltage comparator, configured to convert the output signal from the at least one voltage comparator into a digital signal. In one example, the frequency detector further comprises a digital decoder connected to the analog-to-digital converter and configured to provide the impedance control signal based on a digital signal received from the analog-to-digital converter.

Another embodiment is directed to a coupler module including an electromagnetic coupler system.

Another embodiment is directed to a wireless device that includes a coupler module. The wireless device may also include a transceiver and an antenna, the coupler module being coupled between the antenna and the transceiver.

According to another embodiment, a wireless device includes an example of an electromagnetic coupler system that includes a bidirectional electromagnetic coupler, a transceiver coupled to a first power signal port of the bidirectional electromagnetic coupler, and an antenna coupled to a second power signal port of the bidirectional electromagnetic coupler. The wireless device may further include a sensor selectively connected to the third port and the fourth port of the bidirectional electromagnetic coupler, the sensor configured to receive the forward coupling signal when the bidirectional electromagnetic coupler is operating in the forward mode of operation and to receive the reverse coupling signal when the bidirectional electromagnetic coupler is operating in the reverse mode of operation. In one example, the wireless device further includes a power amplifier coupled between the transceiver and the first power signal port of the bidirectional electromagnetic coupler. In another example, the wireless device further includes an antenna switch module coupled between the second power signal port of the bidirectional electromagnetic coupler and the antenna, and between the antenna and the transceiver. In another example, the wireless device further includes at least one of a baseband subsystem, a power management subsystem, a user interface, at least one memory, and a battery.

According to another embodiment, a self-adjusting electromagnetic coupler system includes a bidirectional electromagnetic coupler including a first power signal port, a second power signal port, a third port, and a fourth port, the electromagnetic coupler including a main line extending between the first and second power signal ports, and a coupled line extending between the third and fourth ports, the electromagnetic coupler configured to generate a forward coupled signal at the third port in response to receiving a first signal at the first power signal port in a forward mode of operation, and to generate a reverse coupled signal at the fourth port in response to receiving a second signal at the second power signal port in a reverse mode of operation. The self-adjusting electromagnetic coupler system also includes at least one adjustable termination impedance and a switching network operable to selectively configure the bidirectional electromagnetic coupler between a forward mode of operation and a reverse mode of operation and to selectively connect the at least one adjustable termination impedance to the fourth port when the bidirectional electromagnetic coupler is in the forward mode of operation and to selectively connect the at least one adjustable termination impedance to the third port when the bidirectional electromagnetic coupler is in the reverse mode of operation. The self-adjusting electromagnetic coupler system further includes a controller configured to control a switching network and a frequency detector configured to determine the frequency of the forward coupled signal and the reverse coupled signal and to provide an impedance control signal to tune the at least one adjustable termination impedance based on the frequency of the forward and reverse coupled signals, the switching network further configured to selectively connect the frequency detector to the third port when the bidirectional electromagnetic coupler is in the forward mode of operation and to selectively connect the frequency detector to the fourth port when the bidirectional electromagnetic coupler is in the reverse mode of operation.

In one example, the at least one adjustable termination impedance includes a first adjustable termination impedance and a second adjustable termination impedance, and the switching network is configured to selectively connect the first adjustable termination impedance to the fourth port when the bidirectional electromagnetic coupler is in the forward mode of operation and to selectively connect the second adjustable termination impedance to the third port when the bidirectional electromagnetic coupler is in the reverse mode of operation. The at least one adjustable termination impedance may comprise a tunable resistor-capacitor-inductor circuit. The at least one adjustable termination impedance may comprise a network of switchable impedance elements. In one example, the network of switchable impedance elements comprises at least one resistive element, at least one capacitive element and at least one inductive element.

In one example, the frequency detector is configured to provide impedance control information to the controller, which is further configured to tune the first and second adjustable termination impedances in response to the impedance control information. In another example, the frequency detector is further configured to provide an impedance control signal based on the impedance control information and apply the impedance control signal to the at least one adjustable termination impedance to tune the at least one adjustable termination impedance.

In one example, the frequency detector includes a plurality of frequency selective components, a respective plurality of envelope detectors coupled to the plurality of frequency selective components, and at least one voltage comparator connected to the plurality of envelope detectors, the at least one voltage comparator configured to compare outputs of the plurality of envelope detectors and generate an output signal in response to the comparison, the frequency detector further configured to provide impedance control information based on the output signal from the at least one voltage comparator. In one example, the plurality of frequency selective components includes a plurality of band pass filters, each having a unique frequency pass band. In another example, the plurality of frequency selective components includes a plurality of narrow band amplifiers. The plurality of envelope detectors may comprise a plurality of diode-based detectors. The frequency detector may further comprise an analog-to-digital converter connected to the at least one voltage comparator, configured to convert the output signal from the at least one voltage comparator into a digital signal. In one example, the frequency detector further comprises a digital decoder connected to the analog-to-digital converter and configured to provide impedance control information based on a digital signal received from the analog-to-digital converter.

According to another embodiment, a self-adjusting electromagnetic coupler assembly includes: an electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port, the electromagnetic coupler including a main line extending between the input port and the output port, and a coupled line extending between the coupled port and the isolated port, the electromagnetic coupler configured to generate a coupled signal at the coupled port in response to receiving an input signal at the input port; an adjustable termination impedance connected to the isolated port; and a frequency detector connected to the coupled port and configured to detect a frequency of the coupled signal and provide impedance control information to tune the adjustable termination impedance based on the frequency of the coupled signal.

In one example, the adjustable termination impedance includes a tunable resistor-capacitor-inductor circuit. In another example, the adjustable termination impedance comprises a network of switchable impedance elements. The network of switchable impedance elements may comprise at least one resistive element, at least one capacitive element and at least one inductive element.

In one example, the self-adjusting electromagnetic coupler assembly further includes a controller coupled to the frequency detector and configured to receive impedance control information from the frequency detector, to generate an impedance control signal based on the impedance control information, and to apply the impedance control signal to the adjustable termination impedance to tune the adjustable termination impedance.

In another example, the electromagnetic coupler is a bidirectional electromagnetic coupler configured to generate a coupled signal at the coupled port in a forward mode of operation and a reverse coupled signal at the isolated port in a reverse mode of operation. The self-adjusting electromagnetic coupler assembly may also include a switch network operable to selectively configure the bi-directional electromagnetic coupler between a forward mode of operation and a reverse mode of operation. In one example, the switching network is further configured to selectively connect the adjustable termination impedance to the isolated port when the bidirectional electromagnetic coupler is in the forward mode of operation and to selectively connect the adjustable termination impedance to the coupled port when the bidirectional electromagnetic coupler is in the reverse mode of operation. The self-adjusting electromagnetic coupler assembly may further include an additional adjustable termination impedance, the switch network being configured to selectively connect the adjustable termination impedance to the isolated port when the bidirectional electromagnetic coupler is in the forward mode of operation and to selectively connect the additional adjustable termination impedance to the coupled port when the bidirectional electromagnetic coupler is in the reverse mode of operation. In one example, the self-adjusting electromagnetic coupler assembly further includes a controller configured to control the switching network. The controller may be coupled to the frequency detector and further configured to receive impedance control information from the frequency detector, to generate an impedance control signal based on the impedance control information, and to apply the impedance control signal to the adjustable termination impedance to tune the adjustable termination impedance.

In one example, the frequency detector includes a plurality of frequency selective components, a respective plurality of envelope detectors coupled to the plurality of frequency selective components, and at least one voltage comparator connected to the plurality of envelope detectors, the voltage comparator configured to compare outputs of the plurality of envelope detectors and generate an output signal in response to the comparison, the frequency detector further configured to provide impedance control information based on the output signal from the at least one voltage comparator. In one example, the plurality of frequency selective components includes a plurality of band pass filters, each having a unique frequency pass band. In another example, the plurality of frequency selective components includes a plurality of narrow band amplifiers. The plurality of envelope detectors may comprise a plurality of diode-based detectors. In one example, the frequency detector further comprises an analog-to-digital converter connected to the at least one voltage comparator, configured to convert the output signal from the at least one voltage comparator into a digital signal. In another example, the frequency detector further comprises a digital decoder connected to the analog-to-digital converter and configured to provide the impedance control information based on a digital signal received from the analog-to-digital converter. The frequency detector may be further configured to provide an impedance control signal based on the impedance control information and apply the impedance control signal to the adjustable termination impedance to adjust the adjustable termination impedance.

Another embodiment is directed to a coupler module that includes a package substrate and an electromagnetic coupler formed on the package substrate. The electromagnetic coupler has an input port, an output port, a coupled port, and an isolated port, the electromagnetic coupler including a main line extending between the input port and the output port, and a coupled line extending between the coupled port and the isolated port, the electromagnetic coupler being configured to generate a coupled signal at the coupled port in response to receiving an input signal at the input port. The coupler module also includes an adjustable termination impedance connected to the isolation port, and a frequency detector mounted on the package substrate, the frequency detector connected to the coupling port and configured to detect a frequency of the coupled signal and provide impedance control information to tune the adjustable termination impedance based on the frequency of the coupled signal.

In one example, the package substrate is a laminate substrate including a first metal layer, a second metal layer, and a dielectric layer interposed between the first and second metal layers, the main line of the electromagnetic coupler is formed in the first metal layer, and the coupling line of the electromagnetic coupler is formed in the second metal layer. In another example, the package substrate is a laminate substrate including at least one metal layer and at least one dielectric layer, the main line and the coupled line of the electromagnetic coupler being formed in the at least one metal layer of the laminate substrate. The coupler module may further include a controller mounted on the package substrate and connected to the frequency detector.

According to another embodiment, a coupler module includes a package substrate, and an electromagnetic coupler assembly die mounted on the package substrate. The electromagnetic coupler assembly die includes: an electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port; an adjustable termination impedance connected to the isolated port; and a frequency detector connected to the coupled port, the electromagnetic coupler further having a main line extending between the input port and the output port, and a coupled line extending between the coupled port and the isolated port, the electromagnetic coupler configured to generate a coupled signal at the coupled port in response to receiving an input signal at the input port, the frequency detector configured to detect a frequency of the coupled signal and provide impedance control information to tune the adjustable termination impedance based on the frequency of the coupled signal. The coupler module also includes a plurality of connection pads for connecting the electromagnetic coupler assembly to an external electronic device.

In one example, the electromagnetic coupler assembly die further includes a controller connected to the frequency detector and the adjustable termination impedance, the controller configured to receive impedance control information from the frequency detector, to generate an impedance control signal based on the impedance control information, and to apply the impedance control signal to the adjustable termination impedance to tune the adjustable termination impedance. The coupler module may further include a controller die mounted on the package substrate and connected to the electromagnetic coupler assembly die, the controller die including a controller configured to receive impedance control information from the frequency detector, to generate an impedance control signal based on the impedance control information, and to apply the impedance control signal to the adjustable termination impedance to tune the adjustable termination impedance.

According to another embodiment, a wireless device includes: a transceiver configured to generate a transmission signal; a power amplifier configured to receive a transmit signal from the transceiver and amplify the transmit signal to provide a first signal; and an electromagnetic coupler assembly. The electromagnetic coupler assembly includes an electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port, an adjustable termination impedance connected to the isolated port, and a frequency detector connected to the coupled port. The electromagnetic coupler also has a main line extending between the input port and the output port, and a coupled line extending between the coupled port and the isolated port, the power amplifier being connected to the input port of the electromagnetic coupler. The electromagnetic coupler is configured to generate a coupled signal at the coupled port in response to receiving the first signal at the input port. The frequency detector is configured to detect a frequency of the coupled signal and provide impedance control information to tune the adjustable termination impedance based on the frequency of the coupled signal. In one example, the wireless device further includes an antenna coupled to the output port of the electromagnetic coupler. The wireless device may also include an antenna switch module coupled between the output port of the electromagnetic coupler and the antenna and between the antenna and the transceiver. In one example, the wireless device further includes a sensor connected to the coupling port of the electromagnetic coupler configured to detect the coupling signal. The wireless device may also include at least one of a baseband subsystem, a power management subsystem, a user interface, and at least one memory.

Other aspects, embodiments, and advantages of these exemplary aspects and embodiments are discussed in detail below. Embodiments disclosed herein may be combined with other embodiments in any manner consistent with at least one of the principles disclosed herein, and references to "an embodiment," "some embodiments," "an alternate embodiment," "various embodiments" or "one embodiment" or the like are not necessarily mutually exclusive and are intended to mean that a particular feature, structure, or characteristic described may be included in at least one embodiment. The appearances of such terms herein are not necessarily all referring to the same embodiment.

Drawings

Various aspects of at least one embodiment are discussed below with reference to the accompanying drawings, which are not drawn to scale. The accompanying drawings are included to provide an illustration and a further understanding of the various aspects and embodiments, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of the invention. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the figure:

FIG. 1 is a block diagram of an example of an electromagnetic coupler;

FIG. 2A is a diagram illustrating an example of an electromagnetic coupler configured for forward power detection;

FIG. 2B is a diagram illustrating an electromagnetic coupler configured for reverse power detection;

FIG. 3A is a diagram of one example of a bi-directional electromagnetic coupler with adjustable termination impedance;

FIG. 3B is a diagram of the bi-directional electromagnetic coupler of FIG. 3A, showing an example of a controller;

FIG. 4A is a graph illustrating one example of an adjustable termination impedance;

FIG. 4B is a graph illustrating another example of an adjustable termination impedance;

FIG. 4C is a graph illustrating another example of an adjustable termination impedance;

FIG. 5 is a diagram of one example of a self-adjusting bi-directional electromagnetic coupler with adjustable termination impedance and integrated frequency detection circuitry;

FIG. 6 is a diagram of another example of a self-adjusting bi-directional electromagnetic coupler with adjustable termination impedance and integrated frequency detection circuitry;

FIG. 7 is a diagram of an example of a self-regulating bi-directional electromagnetic coupler having an adjustable termination impedance and an integrated frequency detection circuit, showing one example of an integrated frequency detection circuit;

FIG. 8 is a diagram of an example of a self-regulating bi-directional electromagnetic coupler having an adjustable termination impedance and an integrated frequency detection circuit, showing another example of an integrated frequency detection circuit;

FIG. 9 is a diagram of an example of a self-regulating bi-directional electromagnetic coupler having an adjustable termination impedance and an integrated frequency detection circuit, showing another example of an integrated frequency detection circuit;

FIG. 10 is a diagram of one example of a multi-band frequency detection circuit for use with a self-adjusting electromagnetic coupler;

FIG. 11A is a diagram of another example of a self-adjusting electromagnetic coupler including an auxiliary coupler for frequency detection;

FIG. 11B is a diagram of another example of a self-adjusting electromagnetic coupler including an auxiliary coupler for frequency detection;

FIG. 12 is an equivalent circuit diagram of a circuit for simulating the performance of an example of a self-adjusting electromagnetic coupler;

FIG. 13A is a graph showing the voltage output from each channel of the modeled frequency detection circuit in response to a simulated 1.5GHz input signal applied at port RF1 of the modeled EM coupler;

FIG. 13B is a graph showing various voltage signals in the simulation circuit of FIG. 12 in response to a 1.5GHz input signal applied at port RF1 of the modeled EM coupler;

FIG. 14A is a graph of S parameter S (3, 1) of the modeled EM coupler of FIG. 12 corresponding to a 1.5GHz input signal applied at port RF1 of the modeled EM coupler;

FIG. 14B is a graph of S parameter S (3, 2) of the modeled EM coupler of FIG. 12 corresponding to a 1.5GHz input signal applied at port RF1 of the modeled EM coupler;

FIG. 14C is a graph of simulated coupler directivity as a function of frequency for the coupler in the equivalent circuit of FIG. 12 and an input signal having a frequency of 1.5 GHz;

FIG. 15A is a graph showing the voltage output from each channel of the modeled frequency detection circuit in response to a simulated 3.5GHz input signal applied at port RF1 of the modeled EM coupler;

FIG. 15B is a graph showing various voltage signals in the analog circuit of FIG. 12 in response to a 3.5GHz input signal applied at port RF1 of the modeled EM coupler;

FIG. 16A is a graph of S parameter S (3, 1) of the modeled EM coupler of FIG. 12 corresponding to a 3.5GHz input signal applied at port RF1 of the modeled EM coupler;

FIG. 16B is a graph of S parameter S (3, 2) of the modeled EM coupler of FIG. 12 corresponding to a 3.5GHz input signal applied at port RF1 of the modeled EM coupler;

FIG. 16C is a graph of simulated coupler directivity as a function of frequency for the coupler in the equivalent circuit of FIG. 12 and an input signal having a frequency of 3.5 GHz;

FIG. 17 is a flow diagram of one example of a method of operating a self-adjusting EM coupler assembly;

FIG. 18A is a block diagram of one example of a module including a self-adjusting electromagnetic coupler;

FIG. 18B is a block diagram of another example of a module including a self-adjusting electromagnetic coupler; and

FIG. 19 is a block diagram of one example of an electronic device including self-adjusting electromagnetic couplers.

Detailed Description

In Electromagnetic (EM) couplers, including RF couplers, the termination impedance on the isolated port plays an important role in controlling the directivity of the coupler. As mentioned above, in conventional RF couplers, the termination impedance is typically at a fixed impedance value, which provides the required directivity only for a specific frequency range. Thus, the directivity will not be optimized when the coupler is operated in a different frequency band outside a particular frequency range. Thus, for example, if the EM coupler is to be used over multiple frequency bands, then an adjustable termination impedance is preferably used. Adjusting the termination impedance of the isolated port electrically connected to the EM coupler may improve the directivity of the EM coupler by providing a desired termination impedance for certain operating conditions, such as the frequency band of the signal to be measured by the EM coupler or the power mode of an electronic system including the EM coupler.

Referring to fig. 2A and 2B, an example of a bi-directional EM coupler 200 with an adjustable termination impedance 210 is shown. Fig. 2A shows an EM coupler 200 configured for forward power measurement. In this configuration, it is desirable for the EM coupler 200 to measure the power in the signal 220 propagating from the first power port 202 to the second power port 204. Thus, the third port 206 of the EM coupler 200 acts as a coupled port and the adjustable termination impedance 210 is connected to the fourth port 208, which acts as an isolated port. Fig. 2B shows the reverse arrangement, where the EM coupler 200 is configured for reverse power measurement, and the signal to be measured 220 propagates from the second power port 204 to the first power port 202. In this configuration, the adjustable termination impedance 210 is connected to the third port 206, which acts as an isolated port, and the measurement occurs at the fourth port 208, which acts as a coupled port. In the reverse power measurement configuration of EM coupler 200, signal 220 may be a reflection of a portion of the signal input at first power port 202, or may be a signal received and input at second power port 204.

The directivity of EM coupler 200 affects the ability of the EM coupler to detect the desired signal 222 at the coupled port and reject unwanted signals 224 that may reduce the measurement sensitivity or accuracy at the coupled port. The higher the directivity, the better. For the forward power measurement configuration shown in fig. 2A, the directivity (D) of the EM coupler in dB is given by:

in the formula (1), P_nIs the power at coupler port n. In the S parameter, this can be written as directivity (dB) — S (3, 1) in dB — S (3, 2) in dB. For the reverse power measurement configuration shown in fig. 2B, the directivity is given as: directivity (dB) is S (4, 2) in dB — S (4, 1) in dB.

As described above, the directivity of the EM coupler 200 is frequency dependent and depends on the termination impedance 210 provided to the isolated port. It is highly desirable to make the directivity of the EM coupler 200 as high as possible over all operating frequencies or frequency ranges of the coupler. Adjusting or tuning the termination impedance 210 may improve the directivity of the EM coupler 200 as the frequency (or frequency band) of the signal 222 changes.

There are a number of ways in which the adjustable termination impedance 210 may be implemented and adjusted. For example, referring to fig. 3A, an example of a bi-directional EM coupler system 300 is shown that includes a controller 310 that controls the mode of operation of the coupler (forward or reverse power detection) and the value of the adjustable termination impedance 210a or 210b present at the isolated port. In this example, EM coupler system 300 includes a set of mode select switches 302, 304, 306, 308 that selectively configure EM coupler 340 for forward or reverse power detection under the control of controller 310. In fig. 3A, EM coupler 340 configured in forward mode is shown. The mode select switches 304 and 306 are closed connecting the third port 206 to the coupled port measurement contact 320 and the fourth port 208 to the adjustable termination impedance 210a, respectively. The mode selection switches 302 and 308 are open. For reverse power measurement, the mode selection switches 304 and 306 may be opened and the mode selection switches 302 and 308 closed to connect the third port 206 to the adjustable termination impedance 210b and the fourth port 208 to another measurement contact 322, respectively.

The controller 310 receives a power signal 330 from a power source (not shown), such as a battery. Controller 310 also receives input control signals 332 that specify various operating parameters of EM coupler 340, such as the desired mode of the coupler and the input frequency of signal 220 to be measured. As will be understood by those skilled in the art, the signal 220 may represent a single carrier frequency, or may represent a range of frequencies, or one or more bands of frequencies. As used herein, the term "input frequency" in the context of a signal to be measured by an EM coupler is intended to mean a signal comprising a single carrier frequency or having a certain, usually relatively narrow, bandwidth covering a range of frequencies. The controller 310 provides a set of mode control signals 334 to actuate the mode select switches 302, 304, 306, and 308 to configure the EM coupler for forward or reverse power measurement, and a set of impedance control signals 336 to tune one of the tunable termination impedances 201a or 210b (tunable termination impedance 210a in the example shown in fig. 3A) connected based on the input frequency information.

Fig. 3B shows one example of a controller 310, which includes a voltage generator 312, a digital decoder 314, and a set of drivers 316. In this example, the voltage generator 312 receives a power signal 330. Voltage generator 312 may be a positive and negative voltage generator and generates voltages (e.g., Vpos and Vneg as shown in fig. 3) to power driver 316. Digital decoder 314 decodes incoming input control signal 332 and controls driver 316 to provide mode control signal 334 and impedance control signal 336.

In fig. 3A and 3B, the adjustable termination impedances 210a, 210B are shown as circuits of adjustable/tunable RLC (resistance-inductance-capacitance), which may include any one or more tunable resistive, inductive, or capacitive elements, or a combination thereof. However, it will be appreciated by those skilled in the art, given the benefit of this disclosure, that the adjustable termination impedance 210 may be implemented in a variety of different ways. For example, in some embodiments, the switching network may selectively electrically couple different termination impedances to the isolated port in response to the impedance control signal 336.

Fig. 4A illustrates one such example, where the adjustable termination impedance 210 includes a plurality of impedances 212 and the associated mode selection switch (302 or 306) includes a corresponding plurality of switches 214, each operable to electrically connect a corresponding one of the impedances 212 to an isolated port of the EM coupler. In response to the one or more impedance control signals 336, any one or more switches 214 may be closed to electrically connect any combination of one or more impedances 212 to the isolated port of the EM coupler to present a desired impedance value at the isolated port. Each impedance 212 may include one or more fixed resistive, capacitive, or inductive elements, or any combination thereof.

In the example shown in fig. 4A, the switch 214 is located between the associated port of the EM coupler 340 and each impedance 212. Fig. 4B shows another configuration in which the adjustable termination impedance 210 comprises a network of individually switchable impedance (resistive, capacitive and inductive) elements 218, each having an associated switch 216. Fig. 4C illustrates another example, where some impedance elements are grouped (e.g., elements 218a and 218B) and associated with a single impedance switch 216a, rather than each impedance element being individually switched, as shown in fig. 4B. In response to the one or more impedance control signals 336, any one or more switches 216 may be closed to electrically connect any combination of one or more switchable impedance elements to the isolated port of the EM coupler to present a desired impedance value at the isolated port. Although the switchable impedance elements are illustrated in fig. 4B and 4C as fixed resistance, capacitance, and inductance elements, any one or more of the impedance elements may be tunable (in response to the impedance control signal 336) as well as switchable.

Using an adjustable termination impedance 210 may improve the directivity of the EM coupler across multiple frequency bands, as the termination impedance may be optimized for different frequencies. However, for proper operation, the controller 310 requires frequency information (e.g., logic states included in the input control signal 332 that define the operating frequency band or indicate the impedance value to be used) to be able to actuate the impedance switches 214 or 216, or otherwise tune the adjustable impedance 210, in order to provide the optimal impedance value for terminating the isolated port.

In some cases, the EM coupler may not be provided with band information. For example, the input control signal 332 may not include input frequency information when received from an external component (i.e., external to the EM coupler), and thus in this case, the controller 310 may not be able to change the value of the termination impedance 210 according to the frequency band of operation.

For this case, aspects and embodiments may provide an integrated mechanism for the EM coupler 340 by which input frequency information is automatically determined, which may then be used to optimize the adjustable termination impedance and the directivity of the coupler without having to rely on receiving frequency information from an external source. The inherent operation of the EM coupler 340 includes extracting (by electromagnetic coupling) a portion of the signal 220 from the main line 110 and providing a coupled signal at the coupled port. According to some embodiments, the coupled signal may be used to extract frequency information, which may then be used to select or adjust the termination impedance 210. For example, as discussed further below, a frequency detection circuit may be connected to the coupled port and may provide information or a control signal that may be used to adjust the termination impedance 210 at the isolated port.

Referring to FIG. 5, there is shown an example of an EM coupler system 300 including a frequency sensing circuit 400, the frequency sensing circuit 400 selectively connectable to the third and fourth ports 206, 208 of the EM coupler 340, optionally depending on the mode of operation of the coupler, to provide a self-adjusting EM coupler assembly 600. For example, frequency detection switches 402 and 404 may be used to connect frequency detection circuit 400 to third port 206 when the coupler is operating in a forward power detection mode (as shown in fig. 5) or to connect frequency detection circuit 400 to fourth port 208 when the coupler is operating in a reverse power detection mode, respectively. In this manner, the frequency detection circuit 400 may be connected to the coupled port of the coupler and used to detect the frequency of the coupled signal. Based on the detected frequency of the coupled signal, the frequency detection circuit may provide impedance control signals 410 and 412 to adjust the termination impedances 210b and 210a, respectively. In some examples, the frequency detection switches 402 and 404 may operate in conjunction with the mode selection switches 302, 304, 306, and 308. If frequency detection is not needed or desired at a given time, both frequency detection switches 402, 404 may be opened to completely disconnect the frequency detection circuit. In the example shown in fig. 5, the frequency detection circuit 400 provides control signals 410, 412 directly to the adjustable termination impedances 210a, 210 b. Accordingly, the frequency detector 400 includes a control circuit 450 configured to generate impedance control signals 410, 412 to appropriately adjust the termination impedances 210a, 210b based on the frequency of the detected coupled signal.

Referring to fig. 6, in another embodiment, the frequency detection circuit 400' may provide frequency information (in the form of signal 414) to the controller 310, and the controller 310 may then use the frequency information to adjust the termination impedances 210a, 210b via the impedance control signal 336, as described above. In one such example, the input control signals 332 may include a signal 414 from a frequency detection circuit and one or more information-containing signals from an external source (e.g., specifying an operating mode or other parameter of the coupler).

The frequency detection circuit may be implemented in various ways. For example, referring to fig. 7, the frequency detection circuit 400 may include envelope detectors 420, 422 that are selectively electrically connected to the third port 206 or the fourth port 208 of the EM coupler 340 (depending on the mode of operation of the coupler) through the frequency detection switches 402, 404. Each of the envelope detectors 420, 422 may be configured to detect coupled signals within a specified frequency range. In the example shown, the frequency detection circuit comprises two envelope detectors 420, 422; however, it will be understood by those skilled in the art that more than two envelope detectors may be included, depending on, for example, the configuration of the envelope detectors (e.g., frequency responsiveness) and the number of different frequency bands or ranges in which the EM coupler is expected to operate. Optionally, one or more amplifiers (not shown in fig. 7) may be used to amplify the coupled signals before they are input to the envelope detectors 420, 422. The outputs of the envelope detectors 420, 422 are provided to a decision circuit, which, based on these outputs, determines a desired impedance value for the adjustable termination impedance 210a or 210b (depending on the mode of operation of the coupler) and provides a control signal 410 or 412 to the adjustable termination impedance 210a or 210b (as shown in fig. 7), or frequency information in the signal 414 to the controller 310, as described above. In the example shown in fig. 7, the decision circuit includes a voltage comparator 424 and a digital logic decoder 426; however, those skilled in the art will appreciate that the decision circuit may be implemented in various other ways. Furthermore, in some examples, the frequency detection circuit 400 may include a sample-and-hold memory function, as frequency detection may typically only occur in the forward power measurement state, but the control signals for the forward and reverse operating states depend on the frequency of the detected coupled signal.

Referring to fig. 8, in one example, each of the envelope detectors 420, 422 may be implemented using a diode 430 and a parallel combination of at least one capacitive element 432 and at least one resistive element 434. In this example, the digital logic decoder 426 includes an inverter 428. As described above, an amplifier 436 may be included to amplify the coupled signal, if desired. In some embodiments, the amplifier 436 may be designed to be narrowband in frequency, thus performing both a frequency selection function and amplification. By detecting the amplitude of the signal output from each narrow band amplifier 436 (using the diode formed by elements 430, 432 and 434 and a capacitance-resistance detection circuit) and comparing these amplitudes using voltage comparator 424, the frequency of the coupled signal can be determined and used to adjust the appropriate termination impedance 210a or 210b, as described above.

Fig. 9 shows another example of an implementation of the frequency detection circuit 400. In this example, frequency selection is provided by a plurality of band pass filters 438. The output of each band pass filter 438 is provided to a voltage comparator 424 by an associated envelope detector (implemented in this example using a combination of a diode 430, a capacitive element 432 and a resistive element 434, as described above), and generates a control signal 410, 412 (or 414), as described above.

The examples shown in fig. 7-9 illustrate arrangements for frequency detection of two different frequencies or frequency bands. However, as noted above, the methods and principles disclosed herein may be readily extended to any number of frequencies or frequency bands. For example, fig. 10 shows an example of a frequency detection circuit 400 that extends to N frequencies or bands, N being an integer greater than 2, and having a channel or channel for each frequency/band. An input signal 440 is received from a coupled port of an associated EM coupler and processed by frequency detection circuit 400 to generate one or more of the control signals 410, 412, 414 as described above. The example shown in fig. 10 includes a band pass filter 438 for each channel; however, the band pass filter may be replaced (or supplemented) with a narrow band amplifier or other frequency selective component as described above. The output from each band pass filter 438 is provided to one input of a respective voltage comparator 424 via an associated envelope detector 442 (implemented in this example using a combination of diode 430, capacitive element 432 and resistive element 434, as described above). A reference voltage 444 is provided at the other input of each voltage comparator 424. The reference voltage 444 provided to each voltage comparator 424 may be the same or may vary between different channels. The output from the voltage comparators 424 is provided to a multi-channel analog-to-digital converter 446, which converts the output received from any of the voltage comparators 424 into a digital signal. The digital signal is provided to a decoder and level shifting circuit 448, which decodes the digital signal to determine the frequency or frequency band of the input signal 440 and generates the appropriate control signal 410, 412, or 414 to tune (or instruct the controller 310 to tune) the appropriate adjustable termination impedance 210 based on the frequency or frequency band of the input signal 440. Particularly in examples where the frequency detection circuit 400 directly controls the adjustable termination impedance 210, the decoder and level shifting circuit 448 may further adjust the amplitude (e.g., voltage level) or other characteristics of the control signals 410, 412 to appropriately drive the adjustable termination impedance 210 or, in some examples, provide the signal 414 having desired characteristics to the controller 310.

In the embodiments discussed above, the frequency detector 400 is selectively electrically connected to the coupling port of the EM coupler 340. According to another embodiment, a dedicated additional or supplemental EM coupler 350 for frequency detection may be placed in series with EM coupler 340 for power measurement. Fig. 11A and 11B show an example of such an arrangement. Fig. 11A shows an example where the frequency detection circuit 400 provides control signals 410, 412 to tune the adjustable termination impedances 210a, 210 b. Fig. 11B shows an example of the frequency detection circuit 400' providing a signal 414 to the controller 310, which in turn provides a signal 332 to tune the adjustable termination impedances 210a, 210B, as described above. In these embodiments, the system includes an additional EM coupler 350 having a main line 352 connected in series with the main line 110 of the EM coupler 340 for power detection/measurement between the two power ports 202, 204. The frequency detection circuit 400 is connected to the coupling port 354 of the additional EM coupler 350. The termination impedance 356 is connected to an isolated port 358 of the additional EM coupler 350. Using the additional coupler 350 for frequency detection may provide the advantage of allowing the coupling factor of the additional coupler 350 to be optimized for the frequency detection circuit 400 without affecting the desired coupling factor of the EM coupler 340. Furthermore, frequency detection may be performed without loading or otherwise interfering with the operation of the EM coupler 340. In the illustrated example, the main line 352 of the additional coupler 350 is shown separate from and connected in series with the main line 110 of the EM coupler 340; however, in other examples, the two couplers may share a common main transmission line. Further, although fig. 11A and 11B show an additional coupler 350 connected on the first power port 202 side of the EM coupler 340, the additional coupler may alternatively be located between the EM coupler 340 and the second power port 204. Additionally, while the termination impedance 456 of the isolation port 358 connected to the additional coupler 350 is shown as an RLC circuit, it may be implemented in various ways, as will be appreciated by those skilled in the art, given the benefit of this disclosure. In some examples, the termination impedance 356 may be the adjustable termination impedance 210 as described above, and may be adjusted under control of a control signal provided by the frequency detection circuit 400 or the controller 310.

Accordingly, aspects and embodiments provide various implementations of a self-adjusting EM coupler system 300 that is capable of detecting a frequency or frequency band of an input signal 220 and automatically adjusting a termination impedance based on the detected frequency information without relying on receiving frequency information from an external source. This approach allows the EM coupler 340 to be optimized over multiple operating frequencies or bands while reducing the input information required to achieve this optimization.

Simulations were conducted to model and demonstrate the self-optimization or self-tuning of examples of EM couplers configured with integrated frequency detection in accordance with the principles and examples discussed above. Fig. 12 is an equivalent circuit diagram showing a simulation (simulation) circuit used for these simulations. The analog circuit includes a four-port EM coupler 510 modeled, and takes into account two frequencies of interest, namely a "mid-band" frequency of 1.5GHz and a "high-band" frequency of 3.5 GHz. The modeled dual-channel frequency detection circuit is connected to the coupled port of the simulated EM coupler 510 and includes a bandpass filter 522 and a diode-based detector and bias circuit 524, similar to the diode-based envelope detector 442 discussed above. Resistors 526 (each simulated to have a value of 1000 ohms) are included to isolate the coupled port of the modeled EM coupler 510 from the modeled frequency detection circuit. Each bandpass filter 522 was modeled as having a passband of 0.1GHz, one centered at about 1.5GHz, and the other centered at about 3.5GHz, with a ripple of 1 dB. The outputs from the two channels of the modeled frequency detection circuit are fed to a comparator 424. The isolated port of the modeled EM coupler 510 is connected via a first switch 512 to a first termination impedance 514, wherein the first termination impedance 514 is configured to present an impedance value that optimizes coupler directivity at a frequency of 1.5GHz, and is connected via a second switch 516 to a second termination impedance 518 optimized for a frequency of 3.5 GHz. Switches 512 and 516 are driven by a switch driver 528 connected to the output of comparator 424. Thus, as described above, based on the frequency detected by the frequency detection circuit (1.5GHz or 3.5GHz), the switch driver 528 actuates the switches 512, 516 to connect the appropriate one of the two termination impedances 514, 518 to the isolated port of the modeled EM coupler 510. Switches 512, 516 are modeled as FET switches; however, those skilled in the art will appreciate that the respective switches 302, 306 may be implemented using any suitable switching device or technique.

The results of simulations using the simulation circuit shown in FIG. 12 are shown in FIGS. 13A-B, 14A-C, 15A-B, and 16A-C. Fig. 13A-B and 14A-C show simulation results for an analog input signal at 1.5GHz, and fig. 15A-B and 16A-C show simulation results for an analog input signal at 3.5 GHz.

FIG. 13A shows the voltage output from each channel of the modeled frequency detection circuit and input to comparator 424, which corresponds to the simulated 1.5GHz input signal at port RF1 of modeled EM coupler 510. Trace 602 represents the output from the "mid-band" channel and trace 604 represents the output from the "high-band" channel. In this example, the analog input signal is at 1.5GHz, so trace 602 has a higher level than trace 604 because the signal is within the pass band of the bandpass filter 522 associated with the mid-band channel, but outside the pass band of the bandpass filter 522 associated with the high-band channel. Thus, the voltage output from comparator 424 (represented by trace 612 in FIG. 13B) indicates that a mid-band frequency of 1.5GHz is detected. As shown in fig. 13B, this detection results in a first switch driver 528, output Vg _ MLB (represented by trace 614 in fig. 13B), turning on to actuate the first switch 512 to connect the first termination impedance 514 optimized for the 1.5GHz frequency to the isolated port of the modeled EM coupler 510, while a second switch driver 528, output Vg _ UHB (represented by trace 616 in fig. 13B), turning off to actuate the second switch 516 to decouple the second termination impedance 518 from the isolated port of the modeled EM coupler 510.

Fig. 14A and 14B show the power ratio of the corresponding S-parameter or coupled signal at the coupled port of the modeled EM coupler relative to the input signal at port RF1 (fig. 14A) and the unwanted reflected signal from port RF2 (fig. 14B) as a function of frequency. Fig. 14C shows the corresponding directivity of the modeled EM coupler 510, which is given by equation (2) in dB, as described above. As can be seen with reference to fig. 14C, the directivity is optimized at a frequency of 1.5 GHz.

FIG. 15A shows the voltage output from each channel of the modeled frequency detection circuit and input to comparator 424, which corresponds to the simulated 3.5GHz input signal at port RF1 of modeled EM coupler 510. Trace 622 represents the output from the "mid-band" channel and trace 624 represents the output from the "high-band" channel. In this example, the analog input signal is at 3.5GHz, so trace 624 has a higher level than trace 622 since the signal is within the pass band of the bandpass filter 522 associated with the high-band channel, but outside the pass band of the bandpass filter 522 associated with the mid-band channel. Thus, the voltage output from comparator 424 (represented by trace 632 in fig. 15B) indicates that a high-band frequency of 3.5GHz is detected. As shown in fig. 15B, this detection results in the second switch driver 528, output Vg _ UHB (represented by trace 634 in fig. 15B), turning on to actuate the second switch 516 to connect the second termination impedance 518 optimized for the 3.5GHz frequency to the isolated port of the modeled EM coupler 510, while the first switch driver 528, output Vg _ MLB (represented by trace 636 in fig. 15B), turning off to actuate the first switch 512 to decouple the first termination impedance 514 from the isolated port of the modeled EM coupler 510.

Fig. 16A and 16B show the corresponding S-parameters as a function of frequency. In particular, fig. 16A shows the power ratio of the coupled signal at the coupled port of the modeled EM coupler relative to the input signal at port RF1 as a function of frequency, and fig. 16B shows the power ratio of the coupled signal at the coupled port of the modeled EM coupler relative to the unwanted reflected signal from port RF2 as a function of frequency. Fig. 16C shows the corresponding directivity of the modeled EM coupler 510, which is given by equation (2) in dB, as described above. As can be seen with reference to fig. 16C, the directivity is optimized at a frequency of 3.5 GHz.

Referring to FIG. 17, a flow diagram of one example of a method of operating a self-adjusting EM coupler assembly or system to improve performance is shown. When the electronic device containing the EM coupler 340 is activated, or when a self-adjusting EM coupler assembly or system is activated, the termination impedance 210 may be set to a default initial value (step 702). In some examples, the default value may be 50 ohms; however, those skilled in the art will appreciate that any default value for the termination impedance 210 may alternatively be selected based on known design or performance parameters. The method may optionally include a step 708 of checking performance parameters of the EM coupler 340, wherein the termination impedance 210 is set to a default value. For example, the performance parameter may include coupler directivity or coupling factor. The measured performance parameter obtained with the termination impedance 210 set to the default value may be used as a baseline for adjusting or optimizing the performance of the EM coupler 340, or for determining whether any adjustments to the value of the termination impedance 210 are needed. For example, if the EM coupler 340 is operating within a specified performance range, tuning of the termination impedance 210 may not be required.

The method may include the step 704 of measuring the frequency of the coupled signal to determine the frequency of the input signal 220, as described above. Based on the detected/measured frequency, the impedance value of the termination impedance 210 may be adjusted (step 706), either directly under the control of the frequency detector 400 or under the control of the controller 310, as described above. After the termination impedance 210 is adjusted, the performance parameters of the EM coupler 340 may be checked (step 708) to determine if any further adjustments to the termination impedance are needed to improve or optimize the coupler performance. The steps 704, 706 and 708 of measuring the frequency of the coupled signal, adjusting the termination impedance 210 and checking the coupler performance, respectively, may be repeated continuously, periodically or under the direction of the controller 310.

Embodiments of the self-adjusting EM coupler system 300 may optionally be packaged with external circuitry into a module that may be used in an electronic device. FIG. 18A is a block diagram of one example of a packaging module 800 that includes an embodiment of a self-adjusting EM coupler assembly 600 and a controller 310. The module 800 includes a package substrate 802 configured to house a plurality of components. In some embodiments, such assemblies may include a self-adjusting EM coupler assembly 600 and a controller 310 having one or more of the features described herein. In the example shown in fig. 18A, the controller 310 and the self-adjusting EM coupler assembly 600 are shown as separate dies mounted on a package substrate 802. However, those skilled in the art will appreciate that other configurations of the module 800 may be implemented. For example, the self-adjusting EM coupler assembly 600 and the controller 310 may be combined into a single die. In another example, the EM coupler 340 may be implemented or fabricated on or in a package substrate using integrated circuit technology. For example, the package substrate 702 may be a laminate substrate including one or more metal layers and one or more dielectric layers, and the main line 110 and the coupled line 112 may be implemented in one or more metal layers of the substrate 702. Fig. 18B is a block diagram of another example of a module 800 in which the EM coupler 340 is implemented in a substrate 802 and connected to a frequency detector 400, the frequency detector 400 being implemented as a die mounted on the substrate 802. In the example of fig. 18B, the frequency detector 400 and the controller 310 are shown as separate dies; however, in other examples, they may be implemented together in a single die.

The self-adjusting EM coupler assembly 600, controller 310 and frequency detector 400 may include various connection terminals or pads 804 that may receive signals from external components or for connecting the module to other assemblies. In some embodiments, other circuits or components 806 may be mounted or formed on the package substrate 802. These other components 806 may optionally be connected to the controller 310 and optionally include one or more connection terminals/pads 808. In some embodiments, module 800 may also include one or more packaging structures, for example, to provide protection and facilitate easier handling of module 800. Such a package structure may include overmolding formed on the package substrate 802 and sized to substantially encapsulate the various dies and components thereon.

The embodiments of the integrated filter-coupler disclosed herein, optionally packaged into a module 800, may be advantageously used in a variety of electronic devices. Examples of electronic devices may include, but are not limited to, consumer electronics, components of consumer electronics, electronic test equipment, cellular communication infrastructure such as base stations, and the like. Examples of electronic devices may include, but are not limited to, mobile phones such as smart phones, telephones, televisions, computer displays, computers, modems, handheld computers, laptop computers, tablet computers, electronic book readers, wearable computers such as smart watches, Personal Digital Assistants (PDAs), microwave ovens, refrigerators, automobiles, stereos, DVD players, CD players, digital music players such as MP3 players, radios, camcorders, cameras, digital cameras, portable memory chips, healthcare monitoring devices, vehicle electronics systems such as automotive electronics systems or avionics systems, home appliances, peripherals, watches, clocks, and the like. Further, the electronic device may include unfinished products.

FIG. 19 is a block diagram of a wireless device 900 including a self-adjusting EM coupler system 300, according to some embodiments. The wireless device 900 may be a cellular phone, a smart phone, a tablet computer, a modem, a communication network, or any other portable or non-portable device configured for voice and/or data communication. For example, wireless device 900 includes an antenna 902 that receives and transmits power signals, and a self-adjusting EM coupler system 300 that may use the transmitted signals for analysis or to adjust subsequent transmissions.

The transceiver 904 is configured to generate signals for transmission and/or process received signals. In some embodiments, the transmit and receive functions may be implemented in separate components (e.g., a transmit module and a receive module) or in the same module.

The signals generated for transmission are received by a Power Amplifier (PA) module 906, which may include one or more PAs' to amplify the one or more generated signals from the transceiver 904. The power amplifier module 906 may be used to amplify various RF or other frequency band transmission signals. For example, the power amplifier module 906 may receive an enable signal that may be used to pulse the output of the power amplifier to help transmit a Wireless Local Area Network (WLAN) signal or any other suitable pulsed signal. The power amplifier module 906 may be configured to amplify any of various types of signals including, for example, Global System for Mobile (GSM) signals, Code Division Multiple Access (CDMA) signals, W-CDMA signals, Long Term Evolution (LTE) signals, or EDGE signals. In some embodiments, the power amplifier module 906 and associated components including switches and the like may be fabricated on a GaAs substrate using, for example, pHEMT or BiFET transistors, or on a silicon substrate using CMOS transistors.

The antenna switching module 908 may be configured to switch between different frequency bands and/or modes, such as between transmit and receive modes, and the like. As shown in fig. 19, in some examples, antenna 902 receives signals provided to transceiver 904 via antenna switch module 908 and low noise amplifier module 910, and also transmits signals from wireless device 900 via transceiver 904, power amplifier module 906, self-adjusting EM coupler system 300, and antenna switch module 908. However, in other examples, multiple antennas may be used. For example, a first antenna may be used for low and mid band signals and a second antenna may be used for high band signals.

The wireless device 900 of fig. 19 also includes a power management system 912 that is connected to the transceiver 904 and manages power for wireless device operation. The power management system 912 may also control the operation of the baseband subsystem 914 and other components of the wireless device 900. The power management subsystem 912 may include or be connected to a power source, such as a battery. The power management system 912 provides power to the wireless device 800 via a power supply in a known manner and includes one or more processors or controllers that can control the transmission of signals.

In one embodiment, baseband subsystem 914 is connected to a user interface 916 to facilitate various inputs and outputs of voice and/or data provided to and received from a user. The baseband subsystem 914 can also be coupled to a memory 918, the memory 918 configured to store data and/or instructions to facilitate operation of the wireless device and/or to provide storage of information for a user.

Still referring to FIG. 19, wireless device 800 includes a self-adjusting EM coupler system 300 that may be used to measure a transmit power signal from power amplifier module 906 and provide one or more coupled signals to sensor module 920. The sensor module 920 may in turn send information to the transceiver 904 and/or directly to the power amplifier module 906 as feedback to adjust the power level of the power amplifier module 906. In this way, the self-adjusting EM coupler system 300 may be used to boost/reduce the power of transmission signals having relatively low/high power. However, it should be understood that the self-adjusting EM coupler system 300 may be used in various other embodiments.

In certain embodiments in which wireless device 900 is a mobile phone with a Time Division Multiple Access (TDMA) architecture, self-adjusting EM coupler system 300 may advantageously manage the amplification of RF transmit power signals from power amplifier module 906. In a mobile phone having a Time Division Multiple Access (TDMA) architecture, such as those found in global system for mobile communications (GSM), Code Division Multiple Access (CDMA), and wideband code division multiple access (W-CDMA) systems, the power amplifier module 906 may be used to move the power envelope up and down within power versus time specified limits. For example, a particular mobile phone may be assigned a transmission time slot for a particular frequency channel. In this case, the power amplifier module 906 may be used to help adjust the power level of one or more RF power signals over time to prevent signal interference from transmissions during the assigned receive timeslot and to reduce power consumption. In such a system, the self-adjusting EM coupler system 300 may be used to measure the power of the power amplifier output signal to help control the power amplifier module 906, as described above.

The implementation shown in fig. 19 is exemplary and not limiting. For example, the implementation of FIG. 19 shows the use of a self-adjusting EM coupler system 300 in connection with the transmission of RF signals, however, it should be understood that the various examples of a self-adjusting EM coupler system 300 discussed herein may also be used with received RF or other signals.

Having described several aspects of at least one embodiment, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only, and it is to be understood that the embodiments of the methods and apparatus discussed herein are not limited in their application to the details of construction and the arrangement of components set forth in the present specification or illustrated in the drawings. The methods and apparatus are capable of other embodiments and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "containing," "involving," and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. References to "or" may be construed as inclusive such that any term described using "or" may refer to any single one, more than one, or all of the described terms. The scope of the invention should be determined by appropriate interpretation of the appended claims and their equivalents.

Claims (80)

1. A self-adjusting electromagnetic coupler assembly, comprising:

an electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port, the electromagnetic coupler including a main line extending between the input port and the output port, and a coupled line extending between the coupled port and the isolated port, the electromagnetic coupler configured to generate a coupled signal at the coupled port in response to receiving an input signal at the input port;

an adjustable termination impedance connected to the isolated port; and

a frequency detector connected to the coupling port and configured to detect a frequency of the coupling signal and provide an impedance control signal to tune the adjustable termination impedance based on the frequency of the coupling signal.

2. The self-adjusting electromagnetic coupler assembly of claim 1 wherein the adjustable termination impedance comprises a tunable resistance-capacitance-inductance circuit.

3. The self-adjusting electromagnetic coupler assembly of claim 1 wherein the adjustable termination impedance comprises a network of switchable impedance elements.

4. A self-adjusting electromagnetic coupler assembly as set forth in claim 3 wherein said network of switchable impedance elements includes at least one resistive element, at least one capacitive element, and at least one inductive element.

5. The self-adjusting electromagnetic coupler assembly of claim 1 further comprising a controller coupled to the frequency detector and configured to receive an impedance control signal from the frequency detector and tune the adjustable termination impedance in response to the impedance control signal.

6. The self-adjusting electromagnetic coupler assembly of claim 1 wherein the electromagnetic coupler, adjustable termination impedance and frequency detector are integrated in a single die.

7. The self-adjusting electromagnetic coupler assembly of claim 1 wherein the frequency detector comprises a plurality of frequency selective components, a corresponding plurality of envelope detectors coupled to the plurality of frequency selective components, and at least one voltage comparator connected to the plurality of envelope detectors and configured to compare outputs of the plurality of envelope detectors and generate an output signal in response to the comparison, the frequency detector further configured to provide an impedance control signal based on the output signal from the at least one voltage comparator.

8. The self-adjusting electromagnetic coupler assembly of claim 7 wherein the plurality of frequency selective components comprises a plurality of band pass filters, each band pass filter having a unique frequency pass band.

9. A self-adjusting electromagnetic coupler assembly as set forth in claim 7 wherein said plurality of frequency selective components comprise a plurality of narrow band amplifiers.

10. The self-adjusting electromagnetic coupler assembly of claim 7 wherein said plurality of envelope detectors comprises a plurality of diode-based detectors.

11. The self-adjusting electromagnetic coupler assembly of claim 7 wherein the frequency detector further comprises an analog-to-digital converter connected to the at least one voltage comparator and configured to convert an output signal from the at least one voltage comparator to a digital signal.

12. The self-adjusting electromagnetic coupler assembly of claim 11 wherein the frequency detector further comprises a digital decoder connected to the analog-to-digital converter and configured to provide an impedance control signal based on a digital signal received from the analog-to-digital converter.

13. A coupler module, comprising:

a package substrate;

an electromagnetic coupler formed on the package substrate, the electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port, the electromagnetic coupler including a main line extending between the input port and the output port, and a coupled line extending between the coupled port and the isolated port, the electromagnetic coupler configured to generate a coupled signal at the coupled port in response to receiving an input signal at the input port;

an adjustable termination impedance connected to the isolated port; and

a frequency detector mounted on a package substrate, the frequency detector connected to the coupling port and configured to detect a frequency of the coupling signal and provide an impedance control signal to tune the adjustable termination impedance based on the frequency of the coupling signal.

14. The coupler module of claim 13, wherein the package substrate is a laminate substrate including a first metal layer in which a main line of the electromagnetic coupler is formed, a second metal layer in which a coupling line of the electromagnetic coupler is formed, and a dielectric layer interposed between the first and second metal layers.

15. The coupler module of claim 13 wherein the packaging substrate is a laminate substrate comprising at least one metal layer and at least one dielectric layer, the main and coupled lines of the electromagnetic coupler being formed in the at least one metal layer of the laminate substrate.

16. The coupler module of claim 13 further comprising a controller mounted on the package substrate and connected to the frequency detector, the controller configured to receive an impedance control signal from the frequency detector and tune the adjustable termination impedance in response to the impedance control signal.

17. The coupler module of claim 13 wherein the frequency detector comprises a plurality of frequency selective components, a corresponding plurality of envelope detectors coupled to the plurality of frequency selective components, and at least one voltage comparator connected to the plurality of envelope detectors and configured to compare outputs of the plurality of envelope detectors and to generate an output signal in response to the comparison, the frequency detector further configured to provide an impedance control signal based on the output signal from the at least one voltage comparator.

18. A coupler module, comprising:

a package substrate;

an electromagnetic coupler assembly die mounted on the package substrate, the electromagnetic coupler assembly die comprising: an electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port; an adjustable termination impedance connected to the isolated port; and a frequency detector connected to the coupled port, the electromagnetic coupler further having a main line extending between the input port and the output port, and a coupled line extending between the coupled port and the isolated port, the electromagnetic coupler being configured to generate a coupled signal at the coupled port in response to receiving an input signal at the input port, the frequency detector being configured to detect a frequency of the coupled signal and provide an impedance control signal to tune the adjustable termination impedance based on the frequency of the coupled signal; and

a plurality of connection pads for connecting the electromagnetic coupler assembly die to an external electronic device.

19. The coupler module of claim 18 further comprising a controller die mounted on the package substrate and connected to the electromagnetic coupler assembly die, the controller die including a controller configured to receive an impedance control signal from the frequency detector and tune the adjustable termination impedance in response to the impedance control signal.

20. The coupler module of claim 18 wherein the frequency detector comprises a plurality of frequency selective components, a corresponding plurality of envelope detectors coupled to the plurality of frequency selective components, and at least one voltage comparator connected to the plurality of envelope detectors and configured to compare outputs of the plurality of envelope detectors and to generate an output signal in response to the comparison, the frequency detector further configured to provide an impedance control signal based on the output signal from the at least one voltage comparator.

21. The coupler module of claim 20 wherein the plurality of frequency selective components comprises a plurality of bandpass filters, each bandpass filter having a unique frequency passband.

22. The coupler module of claim 20 wherein the plurality of frequency selective components comprise a plurality of narrow band amplifiers.

23. A self-adjusting electromagnetic coupler system, comprising:

an electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port, the electromagnetic coupler including a main transmission line extending between the input port and the output port, and a coupled transmission line extending between the coupled port and the isolated port, the electromagnetic coupler configured to generate a coupled signal at the coupled port in response to receiving an input signal at the input port;

an adjustable termination impedance connected to the isolated port;

a frequency detector connected to the coupling port and configured to determine a frequency of the coupled signal and provide an indication of the frequency of the coupled signal; and

a controller connected to the frequency detector and the adjustable termination impedance, the controller configured to receive an indication of a frequency of the coupling signal from the frequency detector and apply a control signal to the adjustable termination impedance to tune the adjustable termination impedance based on the frequency of the coupling signal.

24. The self-adjusting electromagnetic coupler system of claim 23 wherein the adjustable termination impedance comprises a tunable resistance-capacitance-inductance circuit.

25. The self-adjusting electromagnetic coupler system of claim 23 wherein the adjustable termination impedance comprises a network of switchable impedance elements.

26. A self-adjusting electromagnetic coupler system as set forth in claim 25 wherein said network of switchable impedance elements includes at least two resistive elements.

27. A self-adjusting electromagnetic coupler system as set forth in claim 26 wherein said network of switchable impedance elements further comprises at least one capacitive element or at least one inductive element.

28. The self-adjusting electromagnetic coupler system of claim 23 wherein the frequency detector comprises a plurality of frequency selective components, a corresponding plurality of envelope detectors coupled to the plurality of frequency selective components, and at least one voltage comparator connected to the plurality of envelope detectors and configured to compare outputs of the plurality of envelope detectors and produce an indication of the frequency of the coupled signal based on the comparison.

29. A self-adjusting electromagnetic coupler system as set forth in claim 28 wherein said plurality of frequency selective components comprise a plurality of band pass filters, each band pass filter having a unique frequency pass band.

30. A self-adjusting electromagnetic coupler system as set forth in claim 28 wherein said plurality of frequency selective components comprise a plurality of narrow band amplifiers.

31. A self-adjusting electromagnetic coupler system as set forth in claim 28 wherein said plurality of envelope detectors comprises a plurality of diode-based detectors.

32. The self-adjusting electromagnetic coupler system of claim 23 wherein the electromagnetic coupler, adjustable termination impedance, and frequency detector are integrated in a single package.

33. A self-adjusting electromagnetic coupler system, comprising:

a bi-directional electromagnetic coupler having a first power signal port, a second power signal port, a third port, and a fourth port, the electromagnetic coupler including a main line extending between the first and second power signal ports, and a coupled line extending between the third and fourth ports, the electromagnetic coupler configured to generate a forward coupled signal at the third port in response to receiving a first signal at the first power signal port in a forward mode of operation, and to generate a reverse coupled signal at the fourth port in response to receiving a second signal at the second power signal port in a reverse mode of operation;

at least one adjustable termination impedance;

a switch network operable to selectively configure the bidirectional electromagnetic coupler between a forward mode of operation and a reverse mode of operation and to selectively connect the at least one adjustable termination impedance to the fourth port when the bidirectional electromagnetic coupler is in the forward mode of operation and to selectively connect the at least one adjustable termination impedance to the third port when the bidirectional electromagnetic coupler is in the reverse mode of operation;

a controller configured to control the switching network; and

a frequency detector configured to determine a frequency of the forward and reverse coupled signals and provide impedance control information to tune the at least one adjustable termination impedance based on the frequency of the forward and reverse coupled signals, the switching network further configured to selectively connect the frequency detector to the third port when the bi-directional electromagnetic coupler is in a forward mode of operation and to selectively connect the frequency detector to the fourth port when the bi-directional electromagnetic coupler is in a reverse mode of operation.

34. A self-adjusting electromagnetic coupler system as set forth in claim 33 wherein said at least one adjustable termination impedance comprises a first adjustable termination impedance and a second adjustable termination impedance, said switch network being configured to selectively connect said first adjustable termination impedance to said fourth port when said bidirectional electromagnetic coupler is in a forward mode of operation and to selectively connect said second adjustable termination impedance to said third port when said bidirectional electromagnetic coupler is in a reverse mode of operation.

35. The self-adjusting electromagnetic coupler system of claim 33 wherein the at least one adjustable termination impedance comprises a tunable resistor-capacitor-inductor circuit.

36. A self-adjusting electromagnetic coupler system as set forth in claim 33 wherein said at least one adjustable termination impedance comprises a network of switchable impedance elements.

37. A self-adjusting electromagnetic coupler system as set forth in claim 36 wherein said network of switchable impedance elements includes at least one resistive element, at least one capacitive element, and at least one inductive element.

38. The self-adjusting electromagnetic coupler system of claim 34 wherein the frequency detector is configured to provide impedance control information to the controller, the controller further configured to tune the first and second adjustable termination impedances responsive to the impedance control information.

39. The self-adjusting electromagnetic coupler system of claim 33 wherein the frequency detector is further configured to provide an impedance control signal based on the impedance control information and apply the impedance control signal to the at least one adjustable termination impedance to tune the at least one adjustable termination impedance.

40. The self-adjusting electromagnetic coupler system of claim 33 wherein the frequency detector comprises a plurality of frequency selective components, a corresponding plurality of envelope detectors coupled to the plurality of frequency selective components, and at least one voltage comparator connected to the plurality of envelope detectors and configured to compare outputs of the plurality of envelope detectors and generate an output signal in response to the comparison, the frequency detector further configured to provide impedance control information based on the output signal from the at least one voltage comparator.

41. The self-adjusting electromagnetic coupler system of claim 40 wherein the plurality of frequency selective components comprise a plurality of band pass filters, each band pass filter having a unique frequency pass band.

42. A self-adjusting electromagnetic coupler system as set forth in claim 40 wherein said plurality of frequency selective components comprise a plurality of narrow band amplifiers.

43. The self-adjusting electromagnetic coupler system of claim 40 wherein the plurality of envelope detectors comprises a plurality of diode-based detectors.

44. A self-adjusting electromagnetic coupler system as set forth in claim 40 wherein said frequency detector further comprises an analog-to-digital converter connected to said at least one voltage comparator and configured to convert an output signal from said at least one voltage comparator to a digital signal.

45. The self-adjusting electromagnetic coupler system of claim 44 wherein the frequency detector further comprises a digital decoder connected to the analog-to-digital converter and configured to provide impedance control information based on a digital signal received from the analog-to-digital converter.

46. A wireless device, comprising:

a transceiver configured to generate a transmission signal;

a power amplifier configured to receive a transmit signal from the transceiver and amplify the transmit signal to provide a first signal; and

an electromagnetic coupler assembly, comprising: an electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port; an adjustable termination impedance connected to the isolated port; and a frequency detector connected to the coupled port, the electromagnetic coupler further having a main line extending between the input port and the output port, and a coupled line extending between the coupled port and the isolated port, the power amplifier being connected to the input port of the electromagnetic coupler, the electromagnetic coupler being configured to generate a coupled signal at the coupled port in response to receiving the first signal at the input port, and the frequency detector being configured to detect a frequency of the coupled signal and provide impedance control information to tune the adjustable termination impedance based on the frequency of the coupled signal.

47. The wireless device of claim 46 further comprising an antenna coupled to an output port of the electromagnetic coupler.

48. The wireless device of claim 47 further comprising an antenna switch module coupled between the output port of the electromagnetic coupler and the antenna and between the antenna and the transceiver.

49. The wireless device of claim 46 further comprising a sensor of a coupling port connected to the electromagnetic coupler and configured to detect the coupling signal.

50. The wireless device of claim 46 further comprising at least one of a baseband subsystem, a power management subsystem, a user interface, and at least one memory.

51. The wireless device of claim 46 wherein the adjustable termination impedance comprises a tunable resistor-capacitor-inductor circuit.

52. The wireless device of claim 46 wherein the adjustable termination impedance comprises a network of switchable impedance elements.

53. The wireless device of claim 52 wherein the network of switchable impedance elements comprises at least one resistive element, at least one capacitive element, and at least one inductive element.

54. The wireless device of claim 46 wherein the electromagnetic coupler assembly further comprises a controller coupled to the frequency detector and configured to receive an impedance control signal from the frequency detector and tune the adjustable termination impedance responsive to the impedance control signal.

55. The wireless device of claim 46 wherein the frequency detector comprises a plurality of frequency selective components, a corresponding plurality of envelope detectors coupled to the plurality of frequency selective components, and at least one voltage comparator connected to the plurality of envelope detectors and configured to compare outputs of the plurality of envelope detectors and to generate an output signal in response to the comparison, the frequency detector further configured to provide an impedance control signal based on the output signal from the at least one voltage comparator.

56. The wireless device of claim 55, wherein the plurality of frequency selective components comprises a plurality of bandpass filters, each bandpass filter having a unique frequency passband.

57. A wireless device as defined in claim 55, wherein the plurality of frequency selective components comprise a plurality of narrow band amplifiers.

58. The wireless device of claim 55 wherein the plurality of envelope detectors comprises a plurality of diode-based detectors.

59. The wireless device of claim 55 wherein the frequency detector further comprises an analog-to-digital converter connected to the at least one voltage comparator and configured to convert an output signal from the at least one voltage comparator to a digital signal.

60. The wireless device of claim 59 wherein the frequency detector further comprises a digital decoder connected to the analog-to-digital converter and configured to provide an impedance control signal based on a digital signal received from the analog-to-digital converter.

61. A self-adjusting electromagnetic coupler assembly, comprising:

a bi-directional electromagnetic coupler having a first port, a second port, a third port, and a fourth port, the electromagnetic coupler including a main line extending between the first and second ports, and a coupled line extending between the third and fourth ports and disposed physically close to the main line, the bi-directional electromagnetic coupler configured to generate a forward coupled signal at the third port in response to receiving a first signal at the first port in a forward mode of operation and to provide a reverse coupled signal at the fourth port in response to receiving a second signal at the second port in a reverse mode of operation;

an adjustable termination impedance selectively connected to the fourth port when the bidirectional electromagnetic coupler is in a forward mode of operation and selectively connected to the third port when the bidirectional electromagnetic coupler is in a reverse mode of operation; and

a frequency detector selectively connected to a third port when the bidirectional electromagnetic coupler is in a forward mode of operation and configured to detect a frequency of the forward coupling signal and provide an impedance control signal to tune the adjustable termination impedance based on the frequency of the forward coupling signal.

62. The self-adjusting electromagnetic coupler assembly of claim 61 wherein the adjustable termination impedance comprises a tunable resistance-capacitance-inductance circuit.

63. A self-adjusting electromagnetic coupler assembly as set forth in claim 61 wherein said adjustable termination impedance comprises a network of switchable impedance elements.

64. A self-adjusting electromagnetic coupler assembly according to claim 63 wherein said network of switchable impedance elements comprises at least one resistive element, at least one capacitive element and at least one inductive element.

65. A self-adjusting electromagnetic coupler assembly as set forth in claim 61 further comprising a controller coupled to said frequency detector and configured to receive an impedance control signal from said frequency detector and tune said adjustable termination impedance responsive to said impedance control signal.

66. The self-adjusting electromagnetic coupler assembly of claim 61 wherein the bi-directional electromagnetic coupler, adjustable termination impedance and frequency detector are integrated in a single die.

67. The self-adjusting electromagnetic coupler assembly of claim 61 wherein the frequency detector comprises a plurality of frequency selective components, a corresponding plurality of envelope detectors coupled to the plurality of frequency selective components, and at least one voltage comparator connected to the plurality of envelope detectors and configured to compare outputs of the plurality of envelope detectors and generate an output signal in response to the comparison, the frequency detector further configured to provide an impedance control signal based on the output signal from the at least one voltage comparator.

68. A self-adjusting electromagnetic coupler assembly as set forth in claim 67 wherein said plurality of frequency selective components comprise a plurality of band pass filters each having a unique frequency pass band.

69. A self-adjusting electromagnetic coupler assembly as set forth in claim 67 wherein said plurality of frequency selective components comprise a plurality of narrow band amplifiers.

70. A self-adjusting electromagnetic coupler assembly as set forth in claim 67 wherein said plurality of envelope detectors comprises a plurality of diode-based detectors.

71. A self-adjusting electromagnetic coupler assembly as set forth in claim 67 wherein said frequency detector further comprises an analog-to-digital converter connected to said at least one voltage comparator and configured to convert an output signal from said at least one voltage comparator to a digital signal.

72. The self-adjusting electromagnetic coupler assembly of claim 71 wherein the frequency detector further comprises a digital decoder connected to the analog-to-digital converter and configured to provide an impedance control signal based on a digital signal received from the analog-to-digital converter.

73. A self-adjusting electromagnetic coupler assembly as set forth in claim 61 further comprising a mode select switch bank operable to selectively connect said adjustable termination impedance to said third and fourth ports of said bidirectional electromagnetic coupler.

74. A self-adjusting electromagnetic coupler assembly as set forth in claim 73 wherein said frequency detector is also selectively connected to a fourth port when said bidirectional electromagnetic coupler is in a reverse mode of operation and is configured to detect a frequency of a reverse coupled signal.

75. A self-adjusting electromagnetic coupler assembly as set forth in claim 74 further comprising a pair of frequency detection switches operable to selectively connect said frequency detector to one of a third port and a fourth port of said bi-directional electromagnetic coupler.

76. The self-adjusting electromagnetic coupler assembly of claim 73 wherein the adjustable termination impedance comprises a first tunable impedance circuit configured to be selectively connected to a third port by at least one first switch of the bank of mode selection switches and a second tunable impedance circuit configured to be selectively connected to a fourth port by at least one second switch of the bank of mode selection switches.

77. A self-adjusting electromagnetic coupler assembly as set forth in claim 61 further comprising a laminate substrate including at least one metal layer and at least one dielectric layer, said main and coupled lines of said electromagnetic coupler being formed in said at least one metal layer of said laminate substrate.

78. A wireless device, comprising:

a transceiver configured to generate a transmission signal;

an electromagnetic coupler having an input port, an output port, a coupled port, and an isolated port, the electromagnetic coupler including a main line extending between the input and output ports, and a coupled line extending between the coupled and isolated ports and disposed physically close to the main line, the electromagnetic coupler configured to generate a coupled signal at the coupled port in response to receiving a transmit signal at the input port;

an adjustable termination impedance connected to an isolated port of the electromagnetic coupler; and

a frequency detector connected to the coupling port and configured to detect a frequency of the coupling signal and provide an impedance control signal to tune the adjustable termination impedance based on the frequency of the coupling signal.

79. The wireless device of claim 78 further comprising a power amplifier connected between the transceiver and an electromagnetic coupler and configured to amplify the transmit signal.

80. The wireless device of claim 78 wherein the frequency detector comprises a plurality of frequency selective components, a corresponding plurality of envelope detectors coupled to the plurality of frequency selective components, and at least one voltage comparator connected to the plurality of envelope detectors and configured to compare outputs of the plurality of envelope detectors and generate an output signal in response to the comparison, the frequency detector further configured to provide an impedance control signal based on the output signal from the at least one voltage comparator.

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